1. Field
The present invention relates to a solid-state imaging device and a solid-state imaging device useful in a photosensor, a photoelectric conversion device.
2. Description of Related Art
A conventional photosensor in general is a device fabricated by forming a photodiode (PD) in a semiconductor substrate such as silicon (Si), and as for the solid-state imaging device, a flat solid-state imaging device is widely used where PDs are two-dimensionally arranged in a semiconductor substrate and a signal according to a signal charge generated by photoelectric conversion in each PD is read out through a CCD or CMOS circuit.
Development of a photoelectric conversion device using an organic compound is on the way. An organic photoelectric conversion device having a structure in which a plurality of functional layers such as a photoelectric conversion layer generating an electric charge by absorbing light and an electric charge blocking layer suppressing an electric charge injection from an electrode are laminated is disclosed in JP-A-2007-88033 (the term “JP-A” as used herein means an “unexamined published Japanese patent application”). In order to manufacture the imaging device using the organic photoelectric conversion device, it is necessary to perform a color filter forming process or a wire bonding process in addition to the organic compound layer and electrode forming process. In these processes, since the imaging device is heated to 200° C. or more, heat resistance of 200° C. or more is required in the organic photoelectric conversion film used in the imaging device.
JP-A-2006-73856 suggests a photoelectric conversion device in which a photoelectric conversion layer has a plurality of mixed layers of an electron acceptor and an electron donor and having different mixing ratios is disclosed. However, all the mixed layers are used as the photoelectric conversion layer in order to increase a photoelectric conversion efficiency, and there is no description regarding the heat resistance.
JP-A-2009-182095 discloses a configuration in which fullerene is contained in the electric charge blocking layer, not in the photoelectric conversion layer. However, there is no description regarding the heat resistance. Further, fullerene is used for transporting electrons using a characteristic of an n-type organic semiconductor, and used in a hole blocking layer in order to suppress the hole injection from the electrode.
Until now, sensitivity of the photoelectric conversion device using the organic compound is decreased or a dark current thereof is increased when heat is applied, such that more improvement may be required in heat resistance.